Aerosol dispensing devices have been developed that include a dose indicating device to indicate the number of metered doses that have been dispensed from the device, or to indicate the number of doses remaining therein. For example, patients have certain conditions that can be treated with medicaments dispensed in an aerosol and administered to the patient by inhalation. In one format, the aerosol with medicaments are contained in a container, and dispensed in metered, or measured, dosages with an inhalation device, or actuator boot. In such an arrangement, it can be important for the patient to be able to ascertain the number of metered doses remaining in the container, either by an indication of the number remaining therein or by knowledge of the number already dispensed therefrom, such that the patient is not caught unaware with an empty container when in need of the medicament. Thus, it may be important for the inhalation device to provide an accurate indication of either the number of doses remaining in the container, or the number of doses already dispensed therefrom.
In addition, a particular actuator boot may be particularly suited or specially configured for dispensing a particular medicament from the container. Therefore, it may also be important for the container and/or actuator boot to be configured to work with only a corresponding or associated actuator boot and/or container.
Typically, a conventional aerosol container includes a body and a valve stem that can be depressed relative to the body so as to emit the metered dose of aerosol and medicament. The container typically is supplied with a predetermined number of metered doses, generally on the order of about 200, such that the counting of the number of valve stem depressions, and corresponding number of dispensed metered doses, can be directly correlated with the number of doses remaining in the container.
In operation, the container is typically received within a housing of the inhalation device, wherein the valve is brought into engagement with a support block in the housing. The user administers the medicament by moving the container relative to the housing so as to depress the valve stem and internal valve and thereby release a metered dose, which is typically administered to the user through a port or mouthpiece extending from the housing. After the dose is administered, the valve stem, which is typically spring loaded, biases the container away from the support block so as to again move the container relative to the housing. In this way, a metered dose of medicament is administered by each cycle of linear reciprocal movement of the container relative to the housing.
Some actuator boots, or other devices attached to the medicament container, have indicating devices that convert the linear reciprocal movement of the container relative to the housing into a one-way, or single-cycle, movement of an indicator, wherein the indicator identifies the relative fullness of the container, the number of metered doses remaining therein or the number of doses already administered. Often, the indicator is disposed inside the actuator boot. If the container is removed from the actuator boot, for example to clean the actuator boot, a different container may inadvertently be inserted into the actuator boot, thereby corrupting the count or adversely affecting the ability of the actuator boot to properly dispense the substance.
To solve this problem, some devices, including the indicator, are secured to the container, as shown for example in U.S. Pat. No. 6,431,168 to Rand. In the '168 patent to Rand, however, the indicators move with the container as it moves relative to the actuator boot. Therefore, the indicator member moves relative to the viewing window in the actuator boot, which can be a distraction and can create confusion and difficulties in reading the device, thereby calling into question the accuracy and robustness of the device.